Prokaryotic cells don't have a nucleus
Answer:
Since sea urchins are picky, they are used as indicator organisms in public aquariums to determine if the system is functioning properly. This is because they are very "picky" about water quality. If the water is contaminated, the sea urchins will be the first to show signs of stress, spines laying down or falling off. Do use an aquarium filter and do clean up the day after feeding. Any metal exposed to the seawater will corrode and poison the tank. A dying sea urchin will often spawn out and rot out, causing the others in the tank to spawn and die as welll.
Explanation:
Answer:
Simple epithelium is a single layer of cells with every cell in direct contact with the basement membrane that separates it from the underlying connective tissue. In general, it is found where absorption and filtration occur. The thinness of the epithelial barrier facilitates these processes.
A mutation that involves one or a few nucleotides is called
a) mutagen
b) inversion
c) point mutation
d) translocation
Answer:
c) point mutation
Explanation:
When only one or a few nucleotides of a gene are changed by mutation, this is called a point mutation. A point mutation can add one additional nucleotide to the wild type gene or may delete or substitute a nucleotide from it. For example, if a wild type gene sequence is "ATATATATA", then the addition of "C" at the position 4 will change it into "ATACTATATA". This addition of new nucleotide is called point mutation since only one nucleotide is added to the gene. Point mutations can cause serious genetic disorders such as sickle cell anemia.
